Fillings and composite dental materials containing the fillings
The present invention provides a filler which has high water resistance and high acid resistance, and high releasing abilities of ions such as fluorine ions, and can maintain high aesthetic appreciation for a long period of time, and a dental composite material comprising the filler, excellent in water resistance, acid resistance, ion releasability and aesthetic appreciation.
1. A filler comprising at least one metal oxide and at least one water-soluble metal salt, the metal oxide and the water-soluble metal salt each forming an independent phase, characterized in that the water-soluble metal salt phase comprises a crystal of the water-soluble metal salt having an average particle size of from 0.001 to 0.3 μm.
2. The filler according to claim 1 , wherein a number ratio of crystals having a particle size of 0.3 μm or more is 20% or less of the crystals of the water-soluble metal salts.
3. The filler according to claim 1 or 2 , wherein a content of the metal oxide is from 60 to 95% by mol, and a content of the water-soluble metal salt is from 5 to 40% by mol.
4. The filler according to claim 1 or 2 , wherein the metal oxide is at least one compound selected from the group consisting of silicon dioxide, boron oxide, aluminum oxide, titanium oxide, zinc oxide, strontium oxide, yttrium oxide, zirconium oxide, barium oxide, lanthanum oxide and ytterbium oxide.
5. The filler according to claim 4 , wherein the metal oxide comprises at least silicon dioxide.
6. The filler according to claim 1 or 2 , wherein the water-soluble metal salt is:
(i) a fluorine compound; and/or
(ii) at least one compound selected from the group consisting of alkali metal phosphates, alkaline earth metal phosphates, alkali metal carbonates, alkaline earth metal carbonates, alkali metal chlorides and alkaline earth metal chlorides.
7. The filler according to claim 6 , wherein the fluorine compound is sodium fluoride.
8. The filler according to claim 1 or 2 , wherein the photorefractive index is from 1.4 to 1.7.
9. The filler according to claim 1 or 2 , which is a dental filler.
10. A process for preparing the filler according to claim 1 or 2 , comprising mixing a metal oxide and/or a hydrolyzed product of a hydrolysable organometallic compound with an aqueous solution of a water-soluble metal salt, and drying the resulting mixture.
11. The process according to claim 10 , wherein the mixture is a water-containing gel.
12. A dental composite material comprising the filler (a) of claim 9 , a polymerizable monomer (b) and a polymerization initiator (c).
13. The dental composite material according to claim 12 , wherein a content of the filler (a) is from 1 to 90% by weight.